Variable height and lateral position suspension seat post assembly

ABSTRACT

The present invention generally relates to the field of vehicle suspension systems. More specifically, the present invention relates to an improved variable height seat post suspension assembly for bicycles that descends at an angle toward the rear of the bicycle, thereby accomplishing the dual objectives of allowing the rider to reposition his/her body weight both down and back to lower their center of gravity and providing a suspension component to the bicycle. The suspension component of the invention will include a spring and a damping device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This application relates to the field of bicycle suspension and, more particularly, is concerning a variable height seat post that lowers the bicycle's center of gravity while riding, combined with a shock absorbing seat post.

2. Prior Art

The prior art in the field of adjustable suspension bicycle seat posts can be divided into essentially one of two categories: (1) a spring loaded linear design similar in function to a pogo stick that incorporates two telescoping straight tubes that compress downward utilizing either an internal or external spring or other shock absorbing material (such as those disclosed in U.S. Pat. Nos. 7,422,224 B2; 6,581,919 B2; 6,186,487 B1; 5,704,626; 5,236,170 and 5,236,169) and (2) a cantilever style design that allows the seat to pivot downwards toward the rear of the bicycle (such as those disclosed in U.S. Pat. Nos. 5,833,255; 5,346,235; U.S. Pat. Nos. 6,409,130 B1 and 5,833,255).

Previous efforts to develop practical and reliable suspension seat posts have been marginally successful at best, and were the subject of two product safety recalls after cracks in the seat post assembly were discovered.¹ Cantilever and pogo stick style seat posts designed for mountain bikes have never fully been accepted as part of the mainstream in the mountain biking community due to their complexity and unreliability. ¹Consumer Product Safety Commission Alert #02-208 (Jul. 24, 2002) (Cane Creek “Thudbuster” Model; Consumer Product Safety Commission Alert #5-543 (Feb. 18, 2005) (Cannondale 1-X Bicycle Suspension Seat Post).

While providing a suspension component in their design, no known pogo stick type design allows the seat to move both down and back toward the rear of the bicycle. While the above mentioned pogo stick designs contemplate a means for adjusting the rate of tension on the internal suspension spring, none of the pogo stick designs utilize an adjustable hydraulic suspension damping shock to control the spring rebound rate (i.e. the rate of speed the shock spring returns to its fully extended position after being compressed) as the preferred embodiment does.

Of the four cantilever designs mentioned above, two of them incorporate an elastic polymer suspension component as part of their design (U.S. Pat. Nos. 6,409,130 B1 and 5,833,255) but have no spring. Another cantilever design incorporates a spring shock absorber at the center of the cantilever mounts (U.S. Pat. No. 6,270,065 B1) instead of an elastic polymer. U.S. Pat. No. 6,270,065 B1 includes a means for adjusting the rate of tension on the internal suspension spring and contemplates the use of an internal damping shock to control the spring rebound, however its inventor concludes the use of a hydraulic damping shock is not essential for the invention. The present embodiment of this invention differs in that it utilizes both a spring and a hydraulic damping shock.

A major drawback with the cantilever style design is the hazard it presents to users during operation. The cantilever operates in a scissor-like manner when compressing and is capable of crushing fingers or any other body part that can fit between the assembly. Another disadvantage of this design is the amount of complexity and the number of components involved in its assembly that increases the chance of product failure.

When compared to the cantilever style designs, the pogo stick versions are relatively stronger and stand less chance of failure because the seat post assembly travels only up and down and is not making complex movements (i.e. both down and back in a pivoting motion).

3. Benefits of the Present Embodiment over the Prior Art

Traditional bicycle seat posts remain in a fixed position, and most of the rider's weight is placed on the front wheel while cornering. This can cause the front tire to wash out on slippery surfaces. Competitors racing road bikes often will to lean backward during long, fast downhill sections to reduce wind drag and increase their speed.

When compared to the present road bike capabilities, the cornering style of motorcycle road racers is far superior. Motorcyclists are able to lower their center of gravity by hanging off the motorcycle (known as knee dragging), thus distributing their body weight evenly while negotiating a corner. This equalizes the down force applied to both wheel's, giving the rider more traction through the corners since both tires share the burden equally. Unless the rider's weight is balanced evenly so that equal down force is applied to both tires, one tire will reach its maximum level of traction before the other. This results in a loss of traction for the more heavily-burdened tire, while the remaining traction available to the other tire is never fully utilized.

Because the present embodiment incorporates a rearward facing angle in relation to the bicycle frame, the resulting downward travel of the seat post and moves the rider both down and back. This is a distinct improvement over the prior art as it combines the main benefits of the pogo stick and cantalever designs, but eliminates the inherent limitations of each. Specifically, the present embodiment (1) travels up and down like the pogo stick variety without the need for the complex motions found in the cantilever designs; and also (2) travels back toward the rear of the bicycle—something the pogo stick designs will not do.

The present embodiment will especially benefit road bicycle riders engaged in competition. The present embodiment of the invention gives bicyclists the ability to lower the seat down and back on command and while riding. A remote lever releases a locking pin that in turn drops the seat post height down and back at an angle approximately three to four inches. A damping device and guide rod spring slows the decent of the seat post to ease the change in the rider's body position and seat height and absorbs the impacts caused by rough terrain.

By allowing the rider to move their body weight both down and back on the bicycle, the present embodiment equalizes the rider's weight distribution between the front and rear tires and lowers the center of gravity of the bicycle. This increases traction and allows the rider to turn sharper and negotiate corners faster without the fear of a front wheel washout. As a natural consequence, bicyclists are able to adopt a more aggressive riding style in corners and turn harder, sharper, and faster.

The present embodiment is also ideally suited for mountain bikes. Similar to the demands of Motocross racing, the ability to drop the seat level down and back is clearly evident in the marketplace for mountain biking. The present embodiment will provide approximately three inches of suspension travel in the seat post assembly, enhancing the comfort to the rider while reducing any impacts caused by rough terrain and hard corners.

Another distinct advantage of the present embodiment is the relatively non-complex design and reduced number of moving parts. This increases both the reliability and ease of maintenance when compared to the prior art in this field.

Another benefit of the present embodiment is that the damping device. The use of a steering damper configuration eliminates the need for an external oil reservoir found on traditional shock absorbers, resulting in reduced weight.

Legend of Diagrams:

Part # Description

1 Lower mount

1A Frontal view of lower mount

2 Lower mount depicting pull pin assembly

2A Close up of pull pin and groove in guide rod

3 Front view of lower mount with pull pin assembly

4 Bottom cross section view of present embodiment

5 Upper mount

6 Exploded view of present embodiment from frontal position

7 Present embodiment assembled

8 Present embodiment assembled with seat attached

9 Present embodiment as it would appear mounted on a bicycle

SPECIFICATIONS: DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

The present embodiment of the variable height seat post suspension assembly comprise of two main components: The first component is the lower mount assembly that houses a damping device, a guide rod spring, a bearing through which the guide rod travels, and an optional internal locking mechanism connected to a remote control cable system. The optional locking mechanism consists of a pull pin that is attached to a cable and held in place with a spring. The lower mount attaches to a standard seat post at approximately a forty degree angle from the horizontal position for insertion into the seat tube opening within the frame of a bicycle. The second component is the upper mount assembly. The lower portion of this component houses the guide rod and provides a proper seat for the guide rod spring and a means of attaching the piston rod of a damping device. The top portion of the upper mount is shaped to accommodate a standard bicycle seat mounting bracket.

Although the description provided herein relates to a specific embodiment as presently contemplated, it will be understood that the invention in its broadest aspect includes both mechanical, material and functional equivalents of the elements described herein.

1. FIG. 1 is a three dimensional view of lower mount 1, which is preferably fabricated out of a light weight, yet strong material, such as aircraft grade aluminum. Holes in opposite ends of 1 allow the insertion of a hollow tube at one end, and a damping device at the other. Each of these holes is split vertically at the outer ends creating a gap, and one or more holes are drilled perpendicular to the direction of the gap, allowing one or more bolts to be placed through 1 and tightened, creating a clamping effect that holds the hollow tube and the damping device securely. The hollow tube must be of sufficient size to slide into the seat post hole at the top of a bicycle frame, and serves as a replacement for the existing seat post. 1 is angled upwards at approximately a 40 degree angle from a horizontal position near the insertion point of the damping device, forming the elbow shaped bend as depicted in FIG. 1. Although the present embodiments may describe specific angles, materials, and measurements, it is understood that other angles, materials, and measurements could be utilized, so long as such angles, materials and measurements or a combination thereof accomplish an objective of the invention.

2. FIG. 1A is a frontal view of lower mount 1 depicting the gaps at either end of 1. When bolts are placed through these gaps and tightened, this creates a clamping effect that will hold the damping device and the hollow tube in place, respectively. Note also the recessed area in the middle of 1, which serves as a seat for a spring.

3. FIG. 2 is an exploded view of lower mount 1 depicting the function of the pull pin 7 and is connected to a remote control cable system. Pull pin 7 slides laterally inside 1 along an internal cylindrical chamber of sufficient size to allow 7 to slide freely. The internal cylindrical chamber does not extend completely through the front of 1, but does intersect the central hole in 1 where guide rod 3 passes through. Toward the front portion of the internal cylindrical chamber, pull pin 7 spring 9 is seated. 7 is positioned immediately to the rear of 9, so that 7 rides on top of 9. A cable is inserted into a hole drilled in the front end of 7 traveling approximately ½ the length of 7, and another hole is drilled and threaded perpendicular to the hole containing the cable, such that the holes intersect and are perpendicular to each other. Pull-pin screw 8 is inserted and tightened down, thereby holding the cable in place securely. The cable is routed out of a hole in the front of 1 and connects to a remote lever that is operated by the rider. Bushing 5 is pressed into a hole toward the center of 1 allowing guide rod 3 to slide through with minimal friction. The present embodiments require no more than 0.002 degrees of tolerance between 3 and 5, so as to minimize the amount of play between the two surfaces.

4. Guide rod 3 can be configured in two ways. One embodiment incorporates a groove toward the bottom portion of 3, approximately ⅓ of an inch from the bottom and ⅛ inch deep. The width of the groove will be slightly larger than the diameter of 7, allowing 7 to fit into the groove snugly. A close-up of this embodiment is seen in FIG. 2A. Alternatively, no groove is cut into 3.

5. FIG. 3 is a frontal view of lower mount 1. Here, the exit hold for the cable can be seen, along with an expanded view of 7 and 9, which are housed inside the cylindrical chamber of 1 as discussed above.

6. FIG. 4 depicts the present embodiment looking from the bottom up. 3 extends through 5 and comes to rest on top of 7, which is positioned inside a groove in 3 . 7 is held in place by the force of 9, which defaults to the extended position. 7 prohibits 3 from sliding downwards until the remote cable is pulled. This is considered the upright fixed position of the seat post assembly. When the remote cable is pulled, 7 is retracted into the cylindrical internal chamber toward the front of 1. When 7 is completely retracted, 3 is allowed to descend downwards through 5 by the weight of the rider on the seat.

7. FIG. 5 depicts upper mount 10. A vertical gap bisecting the front edge creates a clamping effect when bolts are inserted through horizontal holes passing through the gap and tightened.

8. FIG. 6 is a side view which depicts the assembly of the present embodiment. 4 is inserted into the hole located at the front of 1 and held in place with bolts passing through the gap in front. Damping device 2 is inserted into the rear of 1 and held in place with bolts passing through the gap at the rear of 1. 5 is placed into the guide rod hole located at the center of 1 and pressed into place. 3 is inserted into the front hole of 10 and held in place by the clamping effect created when two bolts are placed in the holes passing through the gap and tightened. The piston rod of 2 is screwed into the threaded hole located at the rear of 10. 3 is fitted lengthwise with guide rod spring 6 and inserted through 5. 6 is seated in the recessed groove located in the center of 1, and at the opposite end is seated in 10 in a recessed groove A bolt is inserted through a hole at the bottom of 10, and threads into a standard seat mounting bracket.

9. FIG. 7 is a depiction of the present embodiment in its assembled form prior to attachment to a standard bicycle seat.

10. FIG. 8 depicts the present embodiment with hollow tube 4 and as it would appear attached to a bicycle seat, ready for insertion into the frame of a bicycle as a replacement for the existing seat post.

11. FIG. 9 depicts the present embodiment assembled and inserted into the frame of a standard road bicycle as a replacement for the existing seat post.

OPERATIONAL CHARACTERISTICS OF THE PRESENT EMBODIMENT

When downward force is applied to the seat, the damping device piston rod, guide rod spring and guide rod attached to the upper mount descend downward toward the lower mount until fully compressed. As the seat descends with the assembly, the guide rod spring and damping device provide suspension that absorbs impacts as the bicycle travels over rough terrain. The force of the compressed spring pushes the guide bar and damping rod back up until the seat returns to its uppermost position when the downward force is removed, such as when the rider lifts his weight up off of the seat.

When the pull-pin locking assembly is included in the embodiment, the seat remains fixed in its uppermost position by the pull-pin, which rides in the groove located toward the bottom portion of the guide rod and held in place by a spring. When the rider pulls a remote lever, the pull pin is retracted from the groove in the guide rod, and the seat and upper mount travel down if downward force is applied. When downward force is applied to the seat, the damping rod and guide rod descend downward until fully compressed. When downward force is removed from the seat, the force of the compressed spring pushes the guide rod and damping rod upwards until the seat returns to its uppermost position. The seat position locks in place automatically when the groove in the guide rod aligns with the pull pin, which is forced back into the groove by a spring without further input from the rider.

The embodiments of the present invention have been described above, but the present invention is not limited to such embodiments, and various design choices may be made within the scope of the present invention. It will be understood that various other modifications, substitutions and changes in the forms and details of the device illustrated, and in its operation, can be made by those skilled in the art without departing in any way from the spirit of the present invention. 

1. A shock absorbing bicycle seat mounting post assembly for placement within a tube of a bicycle frame and for supporting a bicycle seat thereon, said mounting post assembly comprising of: a. an upper mount assembly to which a damping device and guide rod are attached, said upper mount to accommodate the attachment of a bicycle seat; b. a lower mount which includes an upwards bend at approximately forty degrees allowing said upper mount assembly to slide downwards on said guide rod at approximately a forty degree angle toward the rear of a bicycle; c. said lower mount having bisected circular holes for housing said damping device and said hollow tube; and further, a bushing placed near the center of the lower mount as a means of reducing friction caused by the sliding of said guide rod through said lower mount; and further, a recessed circular section for seating a guide rod spring; and d. said lower mount which houses said damping device and a guide rod spring as a means of absorbing shock to the operator, whereby said damping device and said guide rod spring are inserted into a housing and secured in a fixed position; and e. said lower mount having an internal pull pin locking device comprising of a spring and pull pin to which a cable is attached as a means of holding said upper mount in an upright fixed position; and further, allowing said upper mount assembly to slide downwards at approximately a sixty degree angle toward the rear of said bicycle frame along said guide rod by releasing said pull pin remotely by the operator. Whereby the center of gravity of the rider of a bicycle can be lowered by releasing said remote pull pin assembly resulting in the lowering the rider's body position both down and back toward the rear of the bicycle so as to equally distribute the rider's weight between the front and rear wheels, thereby improving the balance, stability, handling characteristics, and traction of the bicycle while at the same time absorbing shocks and other impacts caused by rough terrain.
 2. A means for the operator of a bicycle to lower their center of gravity on a bicycle while riding by operating a remote lever, comprising of the steps of: a. releasing a retractable pull-pin located inside a channel within said lower mount and attached at one end to a cable that is routed to a control lever and operated remotely by the rider of a bicycle, with the opposite end of the retractable pin seated inside a groove formed in the lower end of said guide shaft and held in place by a spring; b. upon releasing said pull-pin, said upper assembly travels downward and back toward the rear of the bicycle from its fixed upright position at approximately a sixty degree angle from a horizontal position when downward force is applied and; c. said top assembly thereafter returning and locking back into its fixed upright position when downward force is removed and the seat is forced back up by said guide rod spring. Whereby the rider of a bicycle can alter the height and lateral position of a bicycle seat while riding by operating a remote control lever, resulting in the lowering the rider's body position both down and back toward the rear of the bicycle so as to equally distribute the rider's weight between the front and rear wheels, thereby lowering the rider's center of gravity on the bicycle and improving the balance, stability, handling characteristics, and traction of the bicycle while at the same time absorbing shocks and other impacts caused by rough terrain. 